fix(xt): satisfy strict-boolean-expressions lint on postOnly checks

[rayBastard]

Summary

Master enabled @typescript-eslint/strict-boolean-expressions and the two if (postOnly) checks from #30059 now fail the lint lane, breaking unrelated PRs whose merge diff includes xt.ts (e.g. #29449). Switched to if (postOnly === true) matching the bybit/bitget idiom — transpiles to is True in Python, ruff-clean

Testing

• Scoped eslint on ts/src/xt.ts — clean
• tsBuild, transpile + ruff — clean, static request tests green in JS, Python, PHP

[carlotestor]

Summary

Replaces two bare if (postOnly) truthiness checks in createOrder/editOrder with explicit if (postOnly === true). Verified this is a real, currently-red lint on master — not a speculative cleanup.

Reproduced on master (9050e94):

ts/src/xt.ts
  2630:13  error  Unexpected nullable boolean value in conditional...  @typescript-eslint/strict-boolean-expressions
  2665:13  error  Unexpected nullable boolean value in conditional...  @typescript-eslint/strict-boolean-expressions

2 problems (2 errors)

On this PR head the same command exits 0.

Root cause

A merge race, not a latent defect. #30082 turned on strict-boolean-expressions (allowNullableBoolean: false) and #30059 added these postOnly blocks — both landed the same day, so #30059 was written against a config that did not yet reject the pattern and never got linted under the new rule.

The nullability comes from the declaration, not the callee: handlePostOnly only ever returns [ true, params ] or [ false, params ], but let postOnly: Bool = undefined (boolean | undefined) is the declared type and destructuring assignment does not narrow it. Hence "nullable boolean".

Correctness

No behaviour change. handlePostOnly never returns undefined, so postOnly === true and postOnly are equivalent for every reachable value — this is pure lint conformance, which is why no test change is warranted (the static fixtures added in #30059 already cover the GTX path).

Scope check

I checked whether this is a partial fix. It is not: of the 8 exchange files touched since the strict-boolean-expressions rollout (alpaca, bingx, bitget, krakenfutures, p2b, pacifica, paradex, xt), xt.ts is the only one that lints red — the other 7 exit 0. The ~40 other bare if (postOnly) sites in ts/src are green because they declare let postOnly = false (non-nullable), so the rule correctly does not fire. This PR closes the whole regression.

Transpile

npx tsx build/transpile.ts xt --force produces exactly the expected 4-line delta and nothing else:

php/xt.php                      | 4 ++--
php/async/xt.php                | 4 ++--
python/ccxt/xt.py               | 4 ++--
python/ccxt/async_support/xt.py | 4 ++--

• Python: if postOnly: → if postOnly is True:
• PHP: if ($postOnly) → if ($postOnly === true)

Both are identity-safe: the Python base handle_post_only returns the literal singletons [True, params] / [False, params], so is True is sound. Go and C# emit IsTrue(IsEqual(postOnly, true)) / isTrue(isEqual(postOnly, true)), matching the 25 existing === true sites already shipped in kucoin/okx. No cross-language risk.

Merge gate: 🟢
Merge probability: 96%

Verdict

Approve. Minimal, correct, and it restores npm run lint to green.

[carlotestor]

Non-blocking, for future reference: the nullability the rule is complaining about originates on line 2628, not at the check. handlePostOnly only ever returns [ true, params ] or [ false, params ], but Bool is boolean | undefined and the destructuring assignment on 2629 doesn't narrow the declared type — so postOnly stays nullable to the type checker.

=== true is the right call here since it matches the 25 existing sites in kucoin/okx and keeps the transpiled output uniform. Worth noting the other option for new code: the ~40 bare if (postOnly) sites elsewhere in ts/src lint clean purely because they declare let postOnly = false, which sidesteps the nullable type at the source. Nothing to change in this PR.

[carlotestor]

Merge digest

Master's new strict-boolean-expressions lint rule tripped on the two if (postOnly) checks in xt.ts, so they now compare explicitly against true like bybit/bitget.

File	Δ	What
ts/src/xt.ts	+2/−2	postOnly truthiness checks

flowchart LR
  xt["xt"]

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ts/src/xt.ts

@@ -2627,7 +2627,7 @@
-        if (postOnly) {
+        if (postOnly === true) {